Investigating the relationship between vitamin B intake and endometriosis: a systematic review and meta-analysis

Introduction: Vitamin B promotes the inactive metabolism of estrogen and inhibits endometrial growth. Accordingly, the present study aimed to examine the relationship between vitamin B intake and endometriosis. Materials and Methods: Databases Scopus, PubMed, ProQuest, Web of Science, Cochrane, Embase, and Google Scholar Search Engine were used for articles published until July 18, 2025. Data was entered into SPSS 19 and analyzed using STATA 14. Results: Generally, administration of vitamins B2 (OR: 0.76, 95% CI: 0.64, 0.90) and B3 (OR: 0.98, 95% CI: 0.96, 1) reduced the risk of endometriosis. However, the relationship between vitamins B1 (OR: 1.04, 95% CI: 0.92, 1.17), B6 (OR: 0.98, 95% CI: 0.89, 1.08), B9 (OR: 1.01, 95% CI: 0.84, 1.21), and B12 (OR: 1.06, 95% CI: 0.98, 1.14) and endometriosis was statistically insignificant. According to the subgroup analysis, vitamin B1 intake in cohort studies increased the risk of endometriosis. Vitamin B2 administration in case-control studies and in the fourth quartile reduced the risk of endometriosis. Vitamin B9 intake, on the other hand, increased the risk of endometriosis in cohort studies and the fourth quartile. Conclusion: Vitamin B2 and B3 intake reduced the risk of endometriosis in women by up to 24% and 2%, respectively. However, to ensure the validity of the results, further studies on this subject are required. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD420251112519) and Research Registry (UIN: reviewregistry2028) websites.